Question

HCS12 Assembly Language:

1. Write a program to convert a decimal number stored at memory location $1010 into a binary number. Store the result in memory location $2000

Answer 1

Step(1). Basic idea of Decimal to binary conversion

Let consider Decimal number have five Digits

If Decimal Is = N1 N2 N3 N4 N5

(Where N1 is Most Significent Number)

Then Binary is = ((((N1x 10) + N2) x 10 + N3) x 10 + N4) x 10 + N5

Step(2). HCS12 program to convert a decimal number stored at memory location $1010 into a binary number. Store the result in memory location $2000

; processing N1

ldaa $1010 ; A = N1 (the most significant digit)

ldab #10   ; B = 10

mul ; operation (1) D = N1 x 10

std $2000 ; store the result in $2000

; processing N2

ldab $1011 ; B = N2

clra ; A = 0 so D = A:B = 00: N2

addd $2000 ;operation (2) d = [$2000]+D = (N1 x 10) + N2

; process N3

ldy #10 ; Y = 10\

emul ; Y:D = D x Y operation (3)

std $2000 ; d = ((N1 x 10) + N2) x 10

ldab $1012 ; B = N3

clra ; A = 0 so D = A:B = 00: N3

addd $2000 ; operation (4) d = ((N1 x 10) + N2) x 10 + N3

; process N4

ldy #10 ; Y = 10

emul ; Y:D = D x Y operation 5

std $2000 ; d = (((N1 x 10) + N2) x 10 + N3) x 10

ldab $1013 ; B = N3

clra ; A = 0 so D = A:B = 00: N4

addd $2000 ;operation (6) d = ((((N1 x 10) + N2) x 10 + N3) x 10) + N4

; process N5

ldy #10 ; Y = 10

emul ; Y:D = D x Y operation (7)

std $2000   ;  d = (((((N1 x 10) + N2) x 10 + N3) x 10) + N4)x 10

ldab $1014   ; B = N5

clra ; A = 0 so D = A:B = 00: N5

addd $2000 ; operation (8) d = ((((((N1 x 10) + N2) x 10 + N3) x 10) + N4)x 10 ) + N5

I Hope it will Helpfull............